/*
 * Copyright 2018 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "src/text/GlyphRun.h"

#include "include/core/SkFont.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkRSXform.h"
#include "include/core/SkScalar.h"
#include "include/private/base/SkTLogic.h"
#include "src/core/SkFontPriv.h"
#include "src/core/SkGlyph.h"
#include "src/core/SkStrikeSpec.h"
#include "src/core/SkTextBlobPriv.h"

#include <cstring>
#include <initializer_list>

class SkPaint;

namespace sktext {
// -- GlyphRun -------------------------------------------------------------------------------------
GlyphRun::GlyphRun(const SkFont &font, SkSpan<const SkPoint> positions, SkSpan<const SkGlyphID> glyphIDs,
    SkSpan<const char> text, SkSpan<const uint32_t> clusters, SkSpan<const SkVector> scaledRotations)
    : fSource{ SkMakeZip(glyphIDs, positions) },
      fText{ text },
      fClusters{ clusters },
      fScaledRotations{ scaledRotations },
      fFont{ font }
{}

GlyphRun::GlyphRun(const GlyphRun &that, const SkFont &font)
    : fSource{ that.fSource }, fText{ that.fText }, fClusters{ that.fClusters }, fFont{ font }
{}

// -- GlyphRunList ---------------------------------------------------------------------------------
GlyphRunList::GlyphRunList(const SkTextBlob *blob, SkRect bounds, SkPoint origin, SkSpan<const GlyphRun> glyphRunList,
    GlyphRunBuilder *builder)
    : fGlyphRuns{ glyphRunList },
      fOriginalTextBlob{ blob },
      fSourceBounds{ bounds },
      fOrigin{ origin },
      fBuilder{ builder }
{}

GlyphRunList::GlyphRunList(const GlyphRun &glyphRun, const SkRect &bounds, SkPoint origin, GlyphRunBuilder *builder)
    : fGlyphRuns{ SkSpan<const GlyphRun>{ &glyphRun, 1 } },
      fOriginalTextBlob{ nullptr },
      fSourceBounds{ bounds },
      fOrigin{ origin },
      fBuilder{ builder }
{}

uint64_t GlyphRunList::uniqueID() const
{
    return fOriginalTextBlob != nullptr ? fOriginalTextBlob->uniqueID() : SK_InvalidUniqueID;
}

bool GlyphRunList::anyRunsLCD() const
{
    for (const auto &r : fGlyphRuns) {
        if (r.font().getEdging() == SkFont::Edging::kSubpixelAntiAlias) {
            return true;
        }
    }
    return false;
}

void GlyphRunList::temporaryShuntBlobNotifyAddedToCache(uint32_t cacheID, SkTextBlob::PurgeDelegate pd) const
{
    SkASSERT(fOriginalTextBlob != nullptr);
    SkASSERT(pd != nullptr);
    fOriginalTextBlob->notifyAddedToCache(cacheID, pd);
}

sk_sp<SkTextBlob> GlyphRunList::makeBlob() const
{
    SkTextBlobBuilder builder;
    for (auto &run : *this) {
        SkTextBlobBuilder::RunBuffer buffer;
        if (run.scaledRotations().empty()) {
            if (run.text().empty()) {
                buffer = builder.allocRunPos(run.font(), run.runSize(), nullptr);
            } else {
                buffer = builder.allocRunTextPos(run.font(), run.runSize(), run.text().size(), nullptr);
                auto text = run.text();
                memcpy(buffer.utf8text, text.data(), text.size_bytes());
                auto clusters = run.clusters();
                memcpy(buffer.clusters, clusters.data(), clusters.size_bytes());
            }
            auto positions = run.positions();
            memcpy(buffer.points(), positions.data(), positions.size_bytes());
        } else {
            buffer = builder.allocRunRSXform(run.font(), run.runSize());
            for (auto [xform, pos, sr] : SkMakeZip(buffer.xforms(), run.positions(), run.scaledRotations())) {
                xform = SkRSXform::Make(sr.x(), sr.y(), pos.x(), pos.y());
            }
        }
        auto glyphIDs = run.glyphsIDs();
        memcpy(buffer.glyphs, glyphIDs.data(), glyphIDs.size_bytes());
    }
    return builder.make();
}

// -- GlyphRunBuilder ------------------------------------------------------------------------------
static SkRect glyphrun_source_bounds(const SkFont &font, const SkPaint &paint,
    SkZip<const SkGlyphID, const SkPoint> source, SkSpan<const SkVector> scaledRotations)
{
    SkASSERT(source.size() > 0);
    const SkRect fontBounds = SkFontPriv::GetFontBounds(font);

    SkSpan<const SkGlyphID> glyphIDs = source.get<0>();
    SkSpan<const SkPoint> positions = source.get<1>();

    if (fontBounds.isEmpty()) {
        // Empty font bounds are likely a font bug.  TightBounds has a better chance of
        // producing useful results in this case.
        auto [strikeSpec, strikeToSourceScale] = SkStrikeSpec::MakeCanonicalized(font, &paint);
        SkBulkGlyphMetrics metrics{ strikeSpec };
        SkSpan<const SkGlyph *> glyphs = metrics.glyphs(glyphIDs);
        if (scaledRotations.empty()) {
            // No RSXForm data - glyphs x/y aligned.
            auto scaleAndTranslateRect = [scale = strikeToSourceScale](const SkRect &in, const SkPoint &pos) {
                return SkRect::MakeLTRB(in.left() * scale + pos.x(), in.top() * scale + pos.y(),
                    in.right() * scale + pos.x(), in.bottom() * scale + pos.y());
            };

            SkRect bounds = SkRect::MakeEmpty();
            for (auto [pos, glyph] : SkMakeZip(positions, glyphs)) {
                if (SkRect r = glyph->rect(); !r.isEmpty()) {
                    bounds.join(scaleAndTranslateRect(r, pos));
                }
            }
            return bounds;
        } else {
            // RSXForm - glyphs can be any scale or rotation.
            SkRect bounds = SkRect::MakeEmpty();
            for (auto [pos, scaleRotate, glyph] : SkMakeZip(positions, scaledRotations, glyphs)) {
                if (!glyph->rect().isEmpty()) {
                    SkMatrix xform =
                        SkMatrix().setRSXform(SkRSXform{ pos.x(), pos.y(), scaleRotate.x(), scaleRotate.y() });
                    xform.preScale(strikeToSourceScale, strikeToSourceScale);
                    bounds.join(xform.mapRect(glyph->rect()));
                }
            }
            return bounds;
        }
    }

    // Use conservative bounds. All glyph have a box of fontBounds size.
    if (scaledRotations.empty()) {
        SkRect bounds;
        bounds.setBounds(positions.data(), SkCount(positions));
        bounds.fLeft += fontBounds.left();
        bounds.fTop += fontBounds.top();
        bounds.fRight += fontBounds.right();
        bounds.fBottom += fontBounds.bottom();
        return bounds;
    } else {
        // RSXForm case glyphs can be any scale or rotation.
        SkRect bounds;
        bounds.setEmpty();
        for (auto [pos, scaleRotate] : SkMakeZip(positions, scaledRotations)) {
            const SkRSXform xform{ pos.x(), pos.y(), scaleRotate.x(), scaleRotate.y() };
            bounds.join(SkMatrix().setRSXform(xform).mapRect(fontBounds));
        }
        return bounds;
    }
}

GlyphRunList GlyphRunBuilder::makeGlyphRunList(const GlyphRun &run, const SkPaint &paint, SkPoint origin)
{
    const SkRect bounds = glyphrun_source_bounds(run.font(), paint, run.source(), run.scaledRotations());
    return GlyphRunList{ run, bounds, origin, this };
}

static SkSpan<const SkPoint> draw_text_positions(const SkFont &font, SkSpan<const SkGlyphID> glyphIDs, SkPoint origin,
    SkPoint *buffer)
{
    SkStrikeSpec strikeSpec = SkStrikeSpec::MakeWithNoDevice(font);
    SkBulkGlyphMetrics storage{ strikeSpec };
    auto glyphs = storage.glyphs(glyphIDs);

    SkPoint *positionCursor = buffer;
    SkPoint endOfLastGlyph = origin;
    for (auto glyph : glyphs) {
        *positionCursor++ = endOfLastGlyph;
        endOfLastGlyph += glyph->advanceVector();
    }
    return SkSpan(buffer, glyphIDs.size());
}

const GlyphRunList &GlyphRunBuilder::textToGlyphRunList(const SkFont &font, const SkPaint &paint, const void *bytes,
    size_t byteLength, SkPoint origin, SkTextEncoding encoding)
{
    auto glyphIDs = textToGlyphIDs(font, bytes, byteLength, encoding);
    SkRect bounds = SkRect::MakeEmpty();
    this->prepareBuffers(glyphIDs.size(), 0);
    if (!glyphIDs.empty()) {
        SkSpan<const SkPoint> positions = draw_text_positions(font, glyphIDs, { 0, 0 }, fPositions);
        this->makeGlyphRun(font, glyphIDs, positions, SkSpan<const char>{}, SkSpan<const uint32_t>{},
            SkSpan<const SkVector>{});
        auto run = fGlyphRunListStorage.front();
        bounds = glyphrun_source_bounds(run.font(), paint, run.source(), run.scaledRotations());
    }

    return this->setGlyphRunList(nullptr, bounds, origin);
}

const GlyphRunList &sktext::GlyphRunBuilder::blobToGlyphRunList(const SkTextBlob &blob, SkPoint origin)
{
    // Pre-size all the buffers, so they don't move during processing.
    this->initialize(blob);

    SkPoint *positionCursor = fPositions;
    SkVector *scaledRotationsCursor = fScaledRotations;
    for (SkTextBlobRunIterator it(&blob); !it.done(); it.next()) {
        size_t runSize = it.glyphCount();
        if (runSize == 0 || !SkFontPriv::IsFinite(it.font())) {
            // If no glyphs or the font is not finite, don't add the run.
            continue;
        }

        const SkFont &font = it.font();
        auto glyphIDs = SkSpan<const SkGlyphID>{ it.glyphs(), runSize };

        SkSpan<const SkPoint> positions;
        SkSpan<const SkVector> scaledRotations;
        switch (it.positioning()) {
            case SkTextBlobRunIterator::kDefault_Positioning: {
                positions = draw_text_positions(font, glyphIDs, it.offset(), positionCursor);
                positionCursor += positions.size();
                break;
            }
            case SkTextBlobRunIterator::kHorizontal_Positioning: {
                positions = SkSpan(positionCursor, runSize);
                for (auto x : SkSpan<const SkScalar>{ it.pos(), glyphIDs.size() }) {
                    *positionCursor++ = SkPoint::Make(x, it.offset().y());
                }
                break;
            }
            case SkTextBlobRunIterator::kFull_Positioning: {
                positions = SkSpan(it.points(), runSize);
                break;
            }
            case SkTextBlobRunIterator::kRSXform_Positioning: {
                positions = SkSpan(positionCursor, runSize);
                scaledRotations = SkSpan(scaledRotationsCursor, runSize);
                for (const SkRSXform &xform : SkSpan(it.xforms(), runSize)) {
                    *positionCursor++ = { xform.fTx, xform.fTy };
                    *scaledRotationsCursor++ = { xform.fSCos, xform.fSSin };
                }
                break;
            }
        }

        const uint32_t *clusters = it.clusters();
        this->makeGlyphRun(font, glyphIDs, positions, SkSpan<const char>(it.text(), it.textSize()),
            SkSpan<const uint32_t>(clusters, clusters ? runSize : 0), scaledRotations);
    }

    return this->setGlyphRunList(&blob, blob.bounds(), origin);
}

std::tuple<SkSpan<const SkPoint>, SkSpan<const SkVector>> GlyphRunBuilder::convertRSXForm(
    SkSpan<const SkRSXform> xforms)
{
    const int count = SkCount(xforms);
    this->prepareBuffers(count, count);
    auto positions = SkSpan(fPositions.get(), count);
    auto scaledRotations = SkSpan(fScaledRotations.get(), count);
    for (auto [pos, sr, xform] : SkMakeZip(positions, scaledRotations, xforms)) {
        auto [scos, ssin, tx, ty] = xform;
        pos = { tx, ty };
        sr = { scos, ssin };
    }
    return { positions, scaledRotations };
}

void GlyphRunBuilder::initialize(const SkTextBlob &blob)
{
    int positionCount = 0;
    int rsxFormCount = 0;
    for (SkTextBlobRunIterator it(&blob); !it.done(); it.next()) {
        if (it.positioning() != SkTextBlobRunIterator::kFull_Positioning) {
            positionCount += it.glyphCount();
        }
        if (it.positioning() == SkTextBlobRunIterator::kRSXform_Positioning) {
            rsxFormCount += it.glyphCount();
        }
    }

    prepareBuffers(positionCount, rsxFormCount);
}

void GlyphRunBuilder::prepareBuffers(int positionCount, int RSXFormCount)
{
    if (positionCount > fMaxTotalRunSize) {
        fMaxTotalRunSize = positionCount;
        fPositions.reset(fMaxTotalRunSize);
    }

    if (RSXFormCount > fMaxScaledRotations) {
        fMaxScaledRotations = RSXFormCount;
        fScaledRotations.reset(RSXFormCount);
    }

    fGlyphRunListStorage.clear();
}

SkSpan<const SkGlyphID> GlyphRunBuilder::textToGlyphIDs(const SkFont &font, const void *bytes, size_t byteLength,
    SkTextEncoding encoding)
{
    if (encoding != SkTextEncoding::kGlyphID) {
        int count = font.countText(bytes, byteLength, encoding);
        if (count > 0) {
            fScratchGlyphIDs.resize(count);
            font.textToGlyphs(bytes, byteLength, encoding, fScratchGlyphIDs.data(), count);
            return SkSpan(fScratchGlyphIDs);
        } else {
            return SkSpan<const SkGlyphID>();
        }
    } else {
        return SkSpan<const SkGlyphID>((const SkGlyphID *)bytes, byteLength / 2);
    }
}

void GlyphRunBuilder::makeGlyphRun(const SkFont &font, SkSpan<const SkGlyphID> glyphIDs,
    SkSpan<const SkPoint> positions, SkSpan<const char> text, SkSpan<const uint32_t> clusters,
    SkSpan<const SkVector> scaledRotations)
{
    // Ignore empty runs.
    if (!glyphIDs.empty()) {
        fGlyphRunListStorage.emplace_back(font, positions, glyphIDs, text, clusters, scaledRotations);
    }
}

const GlyphRunList &sktext::GlyphRunBuilder::setGlyphRunList(const SkTextBlob *blob, const SkRect &bounds,
    SkPoint origin)
{
    fGlyphRunList.emplace(blob, bounds, origin, SkSpan(fGlyphRunListStorage), this);
    return fGlyphRunList.value();
}
} // namespace sktext
